_stackmanager: add support back for fragicmp= and fix man page

_stackmanager did not support the fragicmp= option that _realsetup
did. This commit fixes that.

Although the man page said fragicmp defaults to yes, and the parser
set it to yes as well, I cannot find any openswan 2.x version that
actually defaulted it to yes. Although there was a comment in _realsetup.in
saying IPSECfragicmp = yes, the KLIPS code actually has:

	int sysctl_ipsec_icmp = 0;

(in ipsec_xmit.c in older versions, ipsec_proc.c in newer versions)

So while the parser would claim fragicmp=yes, the KLIPS option actually has
it disabled, as can be seen from performing a modprobe ipsec, and running
cat /proc/sys/net/ipsec/icmp

I changed the parser to set it to "no" per default, and _stackmanager will
only set the proc value to 1 when it sees fragicmp=yes (the non-default)

I also updated the man page.

I opted for changing the man page instead of the code, because as far as I
tracked it down (to openswan 2.3.1) it was already disabled in KLIPS and
_realsetup.in.
_stackmanager: add support back for overridemtu=
KLIPS: change default for hidetos (quality of service) to yes

The ToS field was supposed to be hidden per default using the hidetos=yes
default in "config setup". This was read by _realsetup to set the ipsec.ko
option via /proc/sys/net/ipsec/tos. At least since openswan 2.0.0, and
probably earlier, this was no longer being set.

The default upon loading the KLIPS kernel module is now to enable it.
A separate commit will re-add support to _stackmanager to disable this
when the user specifies hidetos=no in "config setup"
_stackmanager: re-add support for hidetos=

This support was lost when _realsetup/_start* was merged into
_stackmanager
updated changes